Metrology system for substrate deformation measurement

ABSTRACT

Embodiments of the disclosure provide methods and system for inspecting and treating a substrate. In one embodiment, a method is provided including transmitting a first plurality of beams from a diffractive beam splitter to a first surface of a substrate to generate a reflection of a second plurality of beams, wherein the first plurality of beams are spaced apart from each other upon arriving at the first surface of the substrate; receiving the second plurality of beams on a recording surface of an optical device, wherein the second plurality of beams are spaced apart from each other upon arriving at the recording surface; measuring positional information of the second plurality of beams on the recording surface; comparing the positional information of the second plurality of beams to positional information stored in a memory; and storing a result of the comparison in the memory.

BACKGROUND OF THE INVENTION Field of the Invention

Embodiments of the disclosure generally relate to a metrology system andmethods of using the same, and more specifically to methods and a systemfor measuring a deformed state of a substrate due to stress inducedduring processing.

Description of the Related Art

The deposition of a thin film on semiconductor substrates often leads tothe generation of local stresses within the substrate. These stressescan lead to an overall warping of the substrate as well as to localdefects across the substrate, such as on the front side and the backside of the substrate. For example, FIGS. 1A-1B depict an example of afilm layer 56 formed on a substrate 50, which may both be locally and/orglobally deformed. The local and/or global deformations of the substrate50 and the film layer 56 may be caused by the stress resulting from thedifferences between the substrate 50 and the film layer 56, such asstresses caused by the atoms in the film layer 56 not aligning with thelattice structure of the substrate 50. The resulting stress effects thetopography of the surface of the substrate 50 and the surface of thefilm layer 56.

For example, in FIG. 1A, the substrate 50 is deformed and curved, havinga back surface with a curvature C1. The curvature C1 of the back surfaceof the substrate can be defined by a first radius R1. In addition to theglobal back surface curvature C1, areas of the film layer 56 and thesubstrate 50 may have local deformations including curvatures differentfrom the back surface curvature C1. For example, FIG. 1B illustrates aclose-up view of the local deformations of the substrate 50 and filmlayer 56. The local deformations of the substrate 50 and the film layer56 can be due to the thermal expansion or plasma non-uniformities duringa plasma process, or to other non-uniformities present during a processperformed on the substrate 50. Such non-uniformities can cause localizeddeformations for the back surface of the substrate 50 and the frontsurface of the film layer 56. For example, the localized deformations onthe substrate 50 can also be defined by curves, such as a local backsurface curvature C2 with a second radius R2, which is different fromthe first radius R1 of the global back surface curvature C1. Thelocalized curvature C2 may also cause or be adjacent to an unevensurface to the film layer 56 disposed on the substrate 50, leading to alocalized curvature C3 that has a third radius R3 that may all becreated by a stress S1 formed in the film layer 56. The global backsurface curvature C1 formed on the back surface of the substrate 50 maybe at least partially addressed by clamping or restraining the substrateto a substrate support using a substrate holding device, such as anelectrostatic chuck.

However, in most of the situations, the process of clamping orrestraining a substrate is not effective in reducing the localizedcurvatures C2-C3 formed in the substrate. Techniques for removinglocalized deformations (e.g., localized curvatures C2-C3) can be used,such as localized heating of the film layer 56 or localized ionbombardment of the film layer 56. The stress caused by the film layer 56and the resulting localized deformation (e.g., the curvature C3) aregenerally not distributed in a uniform manner across the substrate.Therefore, a map of the deformations on the front or back surface of thesubstrate 50 can be used to enable targeted methods for alleviating thestress caused by deposited films in order to remove the localizeddeformations.

One approach to map the surfaces of substrates is multi-spot local slopemetrology, which is the technique used by the KSA MOS produced byK-Space Associates, Inc. Multi-spot local slope metrology is generallyperformed by directing a laser beam, through an etalon. The etalon canoutput multiple beams from a single input beam by reflections of thesingle input beam in the etalon. The reflections from the etalon can beused to create an array of output beams. The array of output beams canbe directed to different spots on the surface of the substrate to bemeasured.

Despite the capability of being able to direct multiple beams onto asurface of the substrate, multi-spot local slope metrology techniquesusing etalons suffer from a number of drawbacks. First, the intensity ofthe output beams from the etalon can vary for each beam due to changesin intensity caused by the reflections that occur within the etalon.These intensity variations can complicate and the reduce the accuracy ofthe measurements obtained if the intensity variations are not known withenough precision to account for the intensity variations in thecalculations for determining the local slope of the substrate. Second,creating a 2-dimensional array of output beams can complicate theoptical design of the multi-spot local slope metrology tool that usesetalons. For example, multiple etalons are often required to create the2-dimensional array, and the problems caused by intensity variations ofthe output beams can be exacerbated when using multiple etalons. Third,because the output beams are created from reflections of an input beam,the output beams are necessarily related to each other. For example, thespacing between the output beams from the etalon are generally follow adistinct pattern, such as all being the same. The symmetry of the outputbeams from etalon can limit the use of multi-spot local slope metrologytechniques using etalons to measuring substrates with deformations thatare symmetrically spaced across the surface of the substrate.

Therefore, there exists a need for improved methods and systems toperform multi-spot local slope metrology to map surfaces of substrates,so that device performance, product reliability, and yield can beimproved in a more efficient manner.

SUMMARY

Embodiments of the disclosure generally relate to a metrology system andmethods of using the same, and more specifically to methods and a systemfor measuring a deformed state of a substrate due to stress inducedduring processing. In one embodiment, a method of inspecting a substrateis provided. The method includes transmitting a first plurality of beamsfrom a diffractive beam splitter to a first surface of a substrate togenerate a reflection of a second plurality of beams, wherein the firstplurality of beams are spaced apart from each other upon arriving at thefirst surface of the substrate, receiving the second plurality of beamson a recording surface of an optical device, wherein the secondplurality of beams are spaced apart from each other upon arriving at therecording surface, measuring positional information of the secondplurality of beams on the recording surface; comparing the positionalinformation of the second plurality of beams to positional informationstored in a memory and storing a result of the comparison in the memory.

In another embodiment, a method of treating a substrate is provided. Themethod includes transmitting a first plurality of beams from adiffractive beam splitter to a first surface of a substrate to generatea reflection of a second plurality of beams, wherein the first pluralityof beams are spaced apart from each other upon arriving at the firstsurface of the substrate; receiving the second plurality of beams on arecording surface of an optical device, wherein the second plurality ofbeams are spaced apart from each other upon arriving at the recordingsurface; measuring positional information of the second plurality ofbeams on the recording surface; comparing the positional information ofthe second plurality of beams to positional information stored in amemory; and treating the substrate based on the comparison.

In another embodiment, a metrology system is provided. The metrologysystem includes a substrate support configured to receive a substratethereon; an energy source configured to emit a first energy beam; adiffractive beam splitter positioned to receive the first energy beam,the diffractive beam splitter configured to generate a first pluralityof beams from the first energy beam; a beam splitter positioned toreceive the first plurality of beams and output a second plurality ofbeams; a lens positioned between the beam splitter and the substratesupport, the lens adapted to focus the second plurality of beams on afirst surface of the substrate positioned on the substrate support; anoptical device having a recording surface adapted to receive a thirdplurality of beams generated from a reflection of the first plurality ofbeams on the first surface; and a controller configured to measurepositional information of the third plurality of beams on the recordingsurface and compare the positional information of the third plurality ofbeams on the recording surface with positional information stored inmemory.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings.

FIGS. 1A-1B depict a cross sectional view of a substrate having a globalcurvature and localized deformations.

FIG. 2A illustrates a schematic view of a metrology system and asubstrate, according to one embodiment.

FIG. 2B illustrates a schematic view of a metrology system and areference object, according to one embodiment.

FIG. 3 is a top view of a recording surface of an optical device,according to one embodiment.

FIG. 4 is a process flow diagram of a method 400 for inspecting andtreating the substrate 50, according to one embodiment.

FIG. 5 is a schematic, top plan view of an exemplary processing systemthat includes the metrology system of FIG. 2A, according to oneembodiment.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

It is to be noted, however, that the appended drawings illustrate onlyexemplary embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

DETAILED DESCRIPTION

Embodiments of the disclosure describe a metrology system for measuringthe amount of deformation found within a substrate. The metrology systemmay be adapted to detect the variation in the slope across variousregions of the surface of the substrate. In one embodiment, surfacetopography variations of a substrate can be measured by comparingreflections of a matrix of beams from a reference object having a flatsurface relative to reflections of corresponding beams from a surface ofthe substrate.

FIG. 2A illustrates a schematic view of a metrology system 100 and asubstrate 50, according to one embodiment. The film layer 56 describedabove can be formed on the substrate 50 and the substrate 50 and filmlayer 56 can include the curvatures described above (e.g., localizedcurvatures C2-C3). The metrology system 100 can be used to measurelocalized deformations on the substrate 50. For example, the metrologysystem 100 can measure the slope of a back surface 52 (first surface) ofthe substrate 50 facing the metrology system 100. However, in someembodiments a front surface of the substrate 50 or the film layer 56 canbe measured. The metrology system 100 can include a substrate support180 for supporting the substrate 50 during the inspection processperformed by the metrology system 100. In the view shown in FIG. 2A, theZ-direction can be the upward vertical direction, so that the backsurface 52 of the substrate 50 is resting on the substrate support 180.In some embodiments, the substrate support 180 can be an edge ring.Furthermore, in some embodiments the substrate support can be movable inthe X-Y plane, for example by use of an actuator 181 coupled to thesubstrate support 180.

The metrology system 100 includes an energy source 101 configured toemit a first energy beam 102. The energy source 101 can be, for example,a collimated, coherent light source (i.e., coherent electromagneticradiation), such as a laser. In some embodiments, the laser can be a redlaser or a green laser having a power from about 20 mW to about 100 mW,such as about 50 mW.

The metrology system 100 can further include a diffractive beam splitter103 (also known as a diffractive optical element or a multi-spot beamgenerator) positioned to receive the first energy beam 102. Thediffractive optical element 103 can be configured to output a firstplurality of beams 104 (individually shown as 104 a, 104 b, 104 c) fromthe first energy beam 102. The diffractive beam splitter 103 can receivea single input beam from the energy beam 102 and output a 1-dimensionalarray (1×N) or a 2-dimensional beam matrix (M×N) of the first pluralityof beams 104, so that the first plurality of beams 104 can be deliveredto different locations of a surface of the substrate 50 or other target.FIG. 2A shows three beams 104 a, 104 b, 104 c angularly spaced apart inthe X-direction, but the diffractive optical element may also outputadditional beams angularly spaced apart from the beams 104 a, 104 b, 104c in the Y-direction as well as additional beams angularly spaced apartfrom the beams 104 a, 104 b, 104 c in the X-direction. In one example,the diffractive beam splitter is adapted to generate an array of beams,from the provided energy beam 102, where the beams are angularly spacedapart from each other in a first direction and also angularly spacedapart from each other in a second direction.

The array of beams output from the diffractive beam splitter 103 isimproved in a number of ways relative to an array of beams output froman etalon as described above. First, because the diffractive beamsplitter creates output beams from diffraction instead of thetransmissions and reflections described above for the etalon, the outputbeams from the diffractive beam splitter 103 do not suffer from the sameintensity variations as the output beams from an etalon. Because thereare less intensity variations in the output beams produced by thediffractive beam splitter 103, the calculations of the local slope ondifferent locations of the substrate can be simplified. Furthermore, a2-dimensional array can be created one diffractive beam splitter 103,which offers a simpler design relative to the creating a 2-dimensionalarray with a design using multiple etalons. Finally, use of adiffractive beam splitter enables designs that can customize the outputbeams to the deformations expected on the surface of the substrate. Forexample, the diffractive beam splitter can be designed to transmit beamsthat are more closely packed towards the center of the 2-dimensionalarray of output beams than near the edges of the 2-dimensional array ofoutput beams. Thus, specific areas of the surface of the substrate,which are expected to have greater deformations or a greaterconcentration of deformations can be preferentially targeted bydesigning the diffractive beam splitter to direct a greaterconcentration of beams towards those portions of the surface of thesubstrate.

The metrology system 100 can further include a beam splitter 116positioned to receive the first plurality of beams 104 and output asecond plurality of beams 105 (shown individually as 105 a, 105 b, 105c) from transmission of the first plurality of beams 104 through thebeam splitter 116. The beam splitter 116 is also used to directreflected beams from the substrate 50 to an optical device 150 (e.g., acamera) as described in further detail below.

The metrology system 100 can further include a lens 118 positionedbetween the beam splitter 116 and the substrate support 180. The lens118 can be adapted to focus the second plurality of beams 105 on theback surface 52 of the substrate 50 positioned on the substrate support180. The second plurality of beams 105 are spaced apart from each otherupon arriving at the back surface 52 of the substrate 50. The lens 118can be positioned so as to enable the back surface 52 of the substrate50 to be inspected. For example, in one embodiment, the lens 118 can bepositioned below the substrate support 180. Furthermore, inspecting theback surface 52 of the substrate 50 while the back surface 52 is restingon the substrate support 180 can also allow for the substrate 50 to betreated while on the substrate support 180. For example, the substrate50 can be inspected using the methods described below and then the filmlayer 56 on the top surface of the substrate 50 can be treated (e.g.,localized heating or localized ion bombardment of the film layer 56)without moving the substrate 50 from the substrate support 180.

The focusing of the second plurality of beams 105 on the back surface 52of the substrate 50 generates a reflection of a third plurality of beams106 (shown individually as 106 a, 106 b, 106 c). The third plurality ofbeams 106 pass through the lens 118 to the beam splitter 116. The beamsplitter 116 reflects at least a portion of the third plurality of beams106 as a fourth plurality of beams 108 (shown individually as 108 a, 108b, 108 c). The fourth plurality of beams 108 are reflected to theoptical device 150.

The metrology system 100 further includes the optical device 150 havinga recording surface 152 adapted to receive the fourth plurality of beams108 generated from the reflection of the second plurality of beams 105on the back surface 52 of the substrate. The optical device 150 can be acamera, such as a charge-coupled device (CCD) camera, or otherelectromagnetic energy detection device that is able to detect therelative position of the plurality of beams to each other when theplurality of beams are provided to the optical device. The fourthplurality of beams 108 are spaced apart from each other upon arriving atthe recording surface 152.

In some embodiments, the beam fan-out (108 a-108 c) can be so spread outas to be larger than the size of the recording surface 152 of theoptical device 150 (e.g., the CCD detector of the camera). For example,the finite size of the fanned-out beams may make it difficult toaccommodate more than just a few beams directly on the recording surface152 of the optical device 150. In such case, the beams 108 a-108 c canbe allowed to impinge on a separate screen, such as a plane, semi-smoothscattering, or a translucent screen. This separate screen can bearbitrarily large to allow for the recording of as many beams as used ina given application. The optical device 150 can then used to image thespots that are formed on the separate screen. Using a fixed distancebetween the camera and the separate screen, together with a well-focusedimage of the spots on the separate screen can allow for the precisemeasurement of the position of the spots.

The metrology system 100 can further include a controller 44. Thecontroller 44 in communication with the optical device 150 can measurepositional information of the fourth plurality of beams 108 incidentupon the recording surface 152 of the optical device 150. For example,the positional information measured by the controller 44 can include thelocations of each of the fourth plurality of beams 108 on the recordingsurface 152 of the optical device 150. In one embodiment, the positionalinformation can include positions of centroids of each of the fourthplurality of beams 108 on the recording surface 152 of the opticaldevice 150.

The controller 44 generally includes a central processing unit (CPU) 38,a memory 40, and support circuits 42. The CPU 38 may be one of any formof a general purpose computer processor that can be used in anindustrial setting. The support circuits 42 are conventionally coupledto the CPU 38 and may comprise cache, clock circuits, input/outputsubsystems, power supplies, and the like. Software routines loaded inthe memory 40 transform the CPU 38 into a specific purpose computer(controller) 44. The memory 40 can include non-transitory memory thatcan host an application, which, when executed by the CPU 38, caninstruct the components of the metrology system 100 to perform themethods described herein, such as the method 400 described below inreference to FIG. 4.

The controller 44 can be used to operate the metrology system 100, forexample by energizing the energy source 101, controlling andcommunicating with the optical device 150. In some embodiments, thecontroller 44 may also control movement of the substrate support 180through use of the actuator 181 as well as control the transfer of thesubstrate 50 and the reference object 60 (FIG. 2B) onto the substratesupport 180 and removal of the substrate 50 and the reference object 60from the substrate support 180.

The controller 44 can compare the positional information of the fourthplurality of beams 108 on the recording surface 152 with positionalinformation stored in the memory 40. This positional information storedin the memory 40 used for the comparison can be actual locations ofbeams on the recording surface 152 (see FIG. 2B description) orpredicted locations on the recording surface 152 that the fourthplurality of beams 108 would arrive at if the back surface 52 of thesubstrate 50 is entirely flat. The controller 44 can store one or moreresults of this comparison in the memory 40. The comparison between thepositional information of the fourth plurality of beams 108 on therecording surface 152 and the positional information stored in memory 40is described in further detail below in reference to FIG. 3.

FIG. 2B illustrates a schematic view of the metrology system 100 and areference object 60, according to one embodiment. The components shownin FIG. 2B are the same as FIG. 2A except that the reference object 60is placed on the substrate support 180 instead of the substrate 50. Inone embodiment, the reference object is an optical flat. The referenceobject 60 can have a reference surface 62. The reference surface 62 canbe a flat surface or a surface having one or more other specifiedfeatures, such as a surface with a specific slope at a given location onthe surface, or a surface with a specific pattern (e.g., a patterncreated by a lithography process) that can be inspected by the metrologysystem 100 or a similar metrology system. Although the reference surface62 can be other than a flat surface, for the remainder of thisapplication the reference surface is referred to as having a flatsurface unless otherwise specified. In one embodiment, the referenceobject 60 is a semiconductor substrate and the reference surface 62 is aflat, polished surface of the semiconductor substrate. The referenceobject 60 can be positioned on the substrate support 180 and the energysource 101 can be energized as described above in reference to FIG. 2A,so that the beams are emitted by the energy source 101 and directed tothe reference surface 62 by the metrology system 100, and beamsreflecting from the reference surface 62 are directed by the beamsplitter 116 to the recording surface 152 of the optical device 150.

Because the substrate 50 is replaced with the reference object 60, thepath of the reflected beams is different in FIG. 2B than reflected beamsof FIG. 2A. For example, the third plurality of beams 106 reflected fromthe substrate 50 are replaced with a fifth plurality of beams 107 (shownindividually as 107 a, 107 b, 107 c) reflected from the reference object60. Similarly, the fourth plurality of beams 108 reflected from the beamsplitter 116 to the optical device 150 are replaced with a sixthplurality of beams 109 (shown individually as 109 a, 109 b, 109 c).Because the reference surface 62 is flat and the back surface 52 of thesubstrate 50 is not flat, the plurality of beams 109 are incident upondifferent locations of the recording surface 152 of the optical device150 than the fourth plurality of beams 108 described above.

The controller 44 in communication with the optical device 150 canmeasure positional information of the sixth plurality of beams 109incident upon the recording surface 152 of the optical device 150. Forexample, the positional information measured by the controller 44 caninclude the locations of each of the sixth plurality of beams 109 on therecording surface 152 of the optical device 150. In one embodiment, thepositional information can include positions of centroids of each of thesixth plurality of beams 109 on the recording surface 152 of the opticaldevice 150. The controller 44 can compare the positions of the centroidsof each of the fourth plurality of beams 108 (FIG. 2A) with thepositions of the corresponding centroids of each of the sixth pluralityof beams 109.

FIG. 3 is a top view of the recording surface 152 illustrating exemplarylocations where the optical device 150 can sense the fourth plurality ofbeams 108 (FIG. 2A) and the sixth plurality of beams 109 (FIG. 2B). FIG.3 shows positions of where nine of the fourth plurality of beams 108(shown individually as 108 a-108 i) are incident upon the recordingsurface 152 and positions of where nine of the sixth plurality of beams109 (shown individually as 109 a-109 i) are incident upon the recordingsurface 152. Each beam in the fourth plurality of beams 108 has acorresponding beam in the sixth plurality of beams 109. For example, thebeam 108 a corresponds to the beam 109 a because each beam 108 a, 109 aresults from a reflection from the beam 105 a, which arrives atcorresponding locations on the substrate 50 (FIG. 2A) and the referenceobject 60 (FIG. 2B) respectively.

Because the reference surface 62 is flat, the locations of the sixthplurality of beams 109 on the recording surface 152 can serve asreference locations for where the corresponding beams in the fourthplurality of beams 108 should be incident upon the recording surface 152if the back surface 52 of the substrate 50 is flat. For example, thebeam 108 i and the beam 109 i are shown at the same location on therecording surface 152, which indicates that the back surface 52 of thesubstrate 50 is flat at the location where the beam 105 i (not shown)was incident upon the back surface 52 of the substrate 50.

For locations on the back surface 52 of the substrate 50 that are notflat, then the corresponding beams 108, 109 will not coincide at thesame location on the recording surface 152. For example, the location ofa centroid 108 ac of the beam 108 a on the recording surface 152 isspaced apart from a location of a centroid 109 ac of the beam 109 a onthe recording surface 152 indicating that the back surface 52 of thesubstrate 50 is not flat at the location where the beam 105 a (FIG. 2A)was incident upon the back surface 52 of the substrate 50. A greaterdistance between centroids of corresponding beams (e.g., centroids 108ac, 109 ac) indicates a greater slope of the back surface 52 of thesubstrate 50 at the location on the back surface 52 of the substrate 50,which generated the reflection resulting in the corresponding beam inthe fourth plurality of beams 108. For example, the centroid 108 ac ofthe beam 108 a is spaced further apart from the centroid 109 ac of thebeam 109 a on the recording surface 152 than a centroid 108 bc of thebeam 108 b is from a centroid 109 bc of the beam 109 b on the recordingsurface 152. Therefore, the back surface 52 of the substrate 50 has agreater slope at the location upon which the beam 105 a is incident uponthe back surface 52 than the location upon which the beam 105 b isincident upon the back surface 52.

The direction that the centroids of the corresponding beams (e.g., beams108 a, 109 a) are spaced apart on the recording surface 152 can also bemeasured by the controller 44 in communication with the optical device150, and the measurement can be used to determine which direction theback surface 52 is sloping at the location on the back surface 52 of thesubstrate 50, where the corresponding beam in the second plurality ofbeams (e.g., beam 105 a) was incident upon the back surface 52. Thus, avector indicating distance and direction between centroids of each pairof corresponding beams (e.g., beams 108 a, 109 a) on the recordingsurface 152 can be used to calculate the slope at each location on theback surface 52 of the substrate 50 upon which the second plurality ofbeams 105 (FIG. 2A) are incident upon the back surface 52 of thesubstrate 50. For example, a vector 1 a is shown between centroids 108ac, 109 ac of corresponding beams 109 a and 108 a. The controller 44 canuse the slopes at each of the locations on the back surface 52 of thesubstrate 50 to form a map of the back surface 52 of the substrate 50.Furthermore, because the slope of the back surface 52 is often directlyrelated to the slope on the other side of the substrate 50, such as thetop of the film layer 56 shown in FIG. 1B, the slope of the frontsurface of the substrate and/or the slope of the film layer 56 can bedetermined from the slope of the back surface 52 enabling a map of thefront surface of the substrate 50 and/or film layer 56 to be determined.The map of the film layer 56 can then be used for targeted treatment ofthe film layer 56 to reduce the stress caused by the film layer 56. Forexample, localized heating of the film layer 56 or localized ionbombardment of the film layer 56 can be performed to reduce or eliminatedeformations on the substrate 50 and film layer, such as the curvaturesC2-C3 described above in reference to FIG. 1B.

Referring to FIG. 2A, in some embodiments, to create a more detailed mapof the back surface 52 of the substrate 50, the metrology system 100 canbe configured to enable the second plurality of beams 105 to be incidentupon different locations of the back surface 52 of the substrate 50 fordifferent energy beams emitted by the energy source 101. For example, inone embodiment the substrate support 180 is movable in the X-Y plane(e.g., by use of the actuator 181) enabling the second plurality ofbeams 105 for different beams to be incident upon different locations ofthe back surface 52 of the substrate 50 after each movement of thesubstrate support 180 in the X-Y plane. The metrology system 100 canperform a corresponding sequence of movements of the substrate support180 in the X-Y plane with the reference object 60 (FIG. 2B) on thesubstrate support 180 to determine reference points on the recordingsurface 152 that indicate the second plurality of beams 105 beingincident upon a flat surface for each movement of the substrate support180. Thus, the movement of the substrate support 180 can enable a moredetailed map to be created of the back surface 52 of the substrate 50.

FIG. 4 is a process flow diagram of a method 400 for inspecting andtreating the substrate 50, according to one embodiment. Referring alsoto FIG. 2B, at block 402, the energy source 101 is energized and thesecond plurality of beams 105 are delivered to reference surface 62 ofthe reference object 60, wherein the second plurality of beams 105 arespaced apart from each other upon arriving at the reference surface 62of the reference object 60. The second plurality of beams 105 aregenerated from the transmission of the first plurality of beams 104 fromthe diffractive beam splitter 103. The second plurality of beams 105incident upon the reference surface 62 of the reference object 60results in the reflection that generates the sixth plurality of beams109 that are directed from the beam splitter 116 to the optical device150. At block 404, the sixth plurality of beams 109 are received on therecording surface 152 of the optical device 150, wherein the sixthplurality of beams 109 are spaced apart from each other upon arriving atthe recording surface 152. At block 406, positional information of thesixth plurality of beams 109 on the recording surface 152 is measured bythe controller 44 and stored in the memory 40. As described above, thepositional information of the sixth plurality of beams 109 on therecording surface 152 generated from reflections from the flat referencesurface 62 are used as reference points for identifying wherecorresponding reflections from flat portions of the back surface 52 ofthe substrate will be incident upon the recording surface 152.

Blocks 402-406 can often be optional, and there is no requirement toexecute these blocks each time a substrate 50 is inspected. For example,in some embodiments, blocks 402-406 may be executed once and thennumerous substrates 50 may inspected, such as 100 or more substrates.Furthermore, in some embodiments there may be no requirement to executethe blocks 402-406 on a given metrology system 100 as the locations forwhere the fourth plurality of beams 108 (FIG. 2A) will be incident uponthe recording surface 152 when generated from reflections from a flatsurface (e.g., reference surface 62) may already be known fromcalculations or from executing blocks 402-406 on an identical metrologysystem.

Referring also to FIG. 2A, at block 408, the energy source 101 isenergized and the second plurality of beams 105 are delivered to theback surface 52 of the substrate 50, wherein the second plurality ofbeams 105 are spaced apart from each other upon arriving at the backsurface 52 of the substrate 50. The second plurality of beams 105 aregenerated from the transmission of the first plurality of beams 104 fromthe diffractive beam splitter 103. The second plurality of beams 105incident upon the back surface 52 of the substrate 50 results in thereflection that generates the fourth plurality of beams 108 that aredirected from the beam splitter 116 to the optical device 150. At block410, the fourth plurality of beams 108 are received on the recordingsurface 152 of the optical device 150, wherein the fourth plurality ofbeams 108 are spaced apart from each other upon arriving at therecording surface 152. At block 412, positional information of thefourth plurality of beams 108 on the recording surface 152 are measuredby the controller 44 and stored in the memory 40. In some embodiments,the processes performed in blocks 408-410 are repeated multiple timesacross different regions of the substrate surface, as similarlyperformed during blocks 402-406, as discussed above. The position of thedifferent regions and relative positions of the beams within thedifferent regions can be determined and stored in memory along with therelated positional information collected in block 412 by use of theoptical device 150, sensors within the substrate support 180 and thecontroller 44.

At block 414, the positional information of the fourth plurality ofbeams 108 are compared to positional information of the referencepoints, at the same or similar X-Y positional location on the surface ofthe substrate, that are stored in the memory 40 (i.e., the referencepoints that indicate a flat surface). As described above, thiscomparison can be used to determine the slope of the back surface 52 ofthe substrate 50 for the locations on the back surface 52 of thesubstrate 50, where the second plurality of beams 105 were incident uponthe back surface 52. For example, this comparison can determine vectorsfrom the reference points to the location of the fourth plurality ofbeams 108 on the recording surface 152, such as the vector 1 a describedabove in reference to FIG. 3. The results of the comparison (e.g., theslope of the back surface 52 of the substrate 50 at different locationson the back surface 52 or a map of the back surface 52 developed fromthe calculated slopes) can be stored in the memory 40.

At block 416, the substrate 50 can be treated based on the comparisonperformed in block 414. For example, the substrate 50 can be treated byperforming localized heating of the film layer 56 deposited on thesubstrate 50 or localized ion bombardment of the film layer 56 depositedon the substrate 50.

In one embodiment, the reference surface 62 can be a surface of thesubstrate (e.g., rear surface) before a processing step (e.g., adeposition) is performed on the front surface of the substrate. Forexample, blocks 402-406 can be performed on the rear surface of asubstrate before a processing step, such as a deposition step. Next,after block 406, the processing step is performed on the substrate.Then, blocks 408 to 412 are performed. Then, a comparison between themeasurements made in block 406 and the measurements made in block 412 ismade in block 414. Then a treatment (e.g., localized heating) in step416 is performed in an attempt to restore the rear surface of thesubstrate to a condition, which will generate measurements similar tothe measurements that were recorded in block 406. Blocks 408 to 416 canthen be repeated in an iterative fashion as needed to treat thesubstrate in a way that restores the rear surface of the substrate to acondition, which causes the measurements recorded in block 412 to matchor approach matching the measurements that were recorded in block 406before the processing step (e.g., deposition) was performed on thesubstrate. Furthermore, after performing an iterative process on onesubstrate, knowledge of the overall treatment applied to that substratein the multiple executions of block 416 can be used to apply thatoverall treatment in less executions of block 416, such as one executionof block 416, when similar measurements are recorded after an executionof block 412, such as a first execution of block 412. For example,although an iterative process of five executions of block 416 may beused to restore a rear surface of a first substrate to a pre-processingcondition, a subsequent processed substrate may only be treated once torestore the rear surface of the subsequent substrate to thepre-processing condition.

FIG. 5 is a schematic, top plan view of an exemplary processing system500 that includes the metrology system 100 described above, according toone embodiment. In one embodiment, the processing system 500 may be aCentura® integrated processing system, commercially available fromApplied Materials, Inc., located in Santa Clara, Calif. It iscontemplated that other processing systems (including those from othermanufacturers) may be adapted to benefit from the disclosure.

The system 500 includes a vacuum-tight processing platform 504, afactory interface 502, and a system controller 544. The platform 504includes at least one metrology system 510, such as the metrology system100 described above, a plurality of processing chambers 512, 532, 528,520 and at least one load lock chambers 522 that is coupled to a vacuumsubstrate transfer chamber 536. Two load lock chambers 522 are shown inFIG. 5. The factory interface 502 is coupled to the transfer chamber 536by the load lock chambers 522.

In one embodiment, the factory interface 502 comprises at least onedocking station 508 and at least one factory interface robot 514 tofacilitate transfer of substrates. The docking station 508 is configuredto accept one or more front opening unified pod (FOUP). Two FOUPS 506A-Bare shown in the embodiment of FIG. 5. The factory interface robot 514having a blade 516 disposed on one end of the robot 514 is configured totransfer the substrate from the factory interface 502 to the processingplatform 504 for processing through the load lock chambers 522.Optionally, one or more metrology stations 518 may be connected to aterminal 526 of the factory interface 502 to facilitate measurement ofthe substrate from the FOUPS 506A-B.

Each of the load lock chambers 522 has a first port coupled to thefactory interface 502 and a second port coupled to the transfer chamber536. The load lock chambers 522 are coupled to a pressure control system(not shown) which pumps down and vents the load lock chambers 522 tofacilitate passing the substrate between the vacuum environment of thetransfer chamber 536 and the substantially ambient (e.g., atmospheric)environment of the factory interface 502.

The transfer chamber 536 has a vacuum robot 530 disposed therein. Thevacuum robot 530 has a blade 534 capable of transferring substrates 524among the load lock chambers 522, the metrology system 510 and theprocessing chambers 512, 532, 528, 520.

In one embodiment of the system 500, the system 500 may include one ormore metrology systems 510 (e.g., one or more of the metrology systems100 described above) and at least one process chamber 512, 532, 528,520, which may be a deposition chamber, etch chamber, thermal processingchamber (e.g., RTP chamber, laser anneal chamber) or other similar typeof semiconductor processing chamber that may induce stress in asubstrate during normal processing. In some embodiments of the system500, one or more of metrology systems 510 may be disposed within one ormore of the processing chambers 512, 532, 528, 520, the transfer chamber536, the factory interface 502 and/or at least one of the load lockchambers 522.

The system controller 544 is coupled to the processing system 500. Thesystem controller 544, which may include the controller 44 (FIG. 2A) orbe included within the controller 44, can directly control the operationof the process chambers 512, 532, 528, 520 and the metrology system 510of the system 500. Alternatively, the system controller 544 may controlthe computers (or controllers) associated with the process chambers 512,532, 528, 520 and the metrology system 510 (e.g., controller 44) and thesystem 500. In operation, the system controller 544 also enables datacollection and feedback from the respective chambers and metrologysystem 510 to optimize performance of the system 500.

The system controller 544, much like the controller 44 described above,generally includes a central processing unit (CPU) 538, a memory 540,and support circuit 542. The CPU 538 may be one of any form of a generalpurpose computer processor that can be used in an industrial setting.The support circuits 542 are conventionally coupled to the CPU 538 andmay comprise cache, clock circuits, input/output subsystems, powersupplies, and the like. The software routines transform the CPU 538 intoa specific purpose computer (controller) 544. The software routines mayalso be stored and/or executed by a second controller (not shown) thatis located remotely from the system 500.

Thus, embodiments of the disclosure provide a metrology system that maybe utilized to measure film stress, slope of the substrate surface andsurface topography variations on the substrate surface, such as after afilm layer is formed on the substrate. The metrology system disclosedherein are relatively compact relative to conventional metrologydevices, due in at least part to the utilization of relatively simpleoptical elements. Embodiments including the movable substrate supportcan create detailed maps of the surface of the substrate withoutincluding complicated optics. The compact size of the metrology systemsmay ease installation of the metrology system into a manufacturing tool(e.g., an existing manufacturing tool), such as a processing system, soas to save manufacturing cost and transportation time. Thus, a low costand easily implemented metrology system is obtained to facilitatemeasurement of film stress, slope of surface of the substrate andsurface topography variations on a substrate surface without adverselyincreasing manufacturing cycle time and cost.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method of inspecting a substrate comprising:transmitting a first plurality of beams from a diffractive beam splitterto a first surface of a substrate to generate a reflection of a secondplurality of beams, wherein the first plurality of beams are spacedapart from each other upon arriving at the first surface of thesubstrate; receiving the second plurality of beams on a recordingsurface of an optical device, wherein the second plurality of beams arespaced apart from each other upon arriving at the recording surface;determining a position on the recording surface for each beam of thesecond plurality of beams; for each position of each beam of the secondplurality of beams on the recording surface, comparing that individualposition to an individual position on the recording surface of acorresponding beam from a third plurality of beams stored in a memory,wherein the third plurality of beams are generated by a reflection of afourth plurality of beams incident upon a surface of an object otherthan the substrate; determining a difference between the comparedindividual positions; and storing a result of the comparison in thememory.
 2. The method of claim 1, wherein the position of each beam ofthe second plurality of beams on the recording surface and the positionof each beam of the third plurality of beams on the recording surfaceeach comprise a position of a centroid of the corresponding beam on therecording surface.
 3. The method of claim 2, wherein comparing theindividual position of each beam of the second plurality of beams to theindividual position of the corresponding beam of the third plurality ofbeams comprises determining a vector from the centroid of each beam ofthe third plurality of beams on the recording surface to the centroid ofeach corresponding beam of the second plurality of beams on therecording surface.
 4. The method of claim 3, further comprisingcalculating a local slope of the first surface of the substrate for eachlocation on the first surface on which the first plurality of beams arereceived based on the determined vectors.
 5. The method of claim 1,wherein a film is deposited on a second surface of the substrate and thefirst surface opposes the second surface.
 6. The method of claim 1,wherein the optical device is a charge-coupled device (CCD).
 7. Themethod of claim 1, wherein an outer portion of the first surface of thesubstrate is disposed on a substrate support when the first plurality ofbeams arrive at the first surface.
 8. A method of treating a substratecomprising: transmitting a first plurality of beams from a diffractivebeam splitter to a first surface of a substrate to generate a reflectionof a second plurality of beams, wherein the first plurality of beams arespaced apart from each other upon arriving at the first surface of thesubstrate; receiving the second plurality of beams on a recordingsurface of an optical device, wherein the second plurality of beams arespaced apart from each other upon arriving at the recording surface;determining a position on the recording surface for each beam of thesecond plurality of beams; for each position of each beam of the secondplurality of beams on the recording surface, comparing that individualposition to an individual position on the recording surface of acorresponding beam from a third plurality of beams stored in a memory,wherein the third plurality of beams are generated by a reflection of afourth plurality of beams incident upon a surface of an object otherthan the substrate; determining a difference between the comparedindividual positions; storing a result of the comparison in the memory;and treating the substrate based on the comparison.
 9. The method ofclaim 8, wherein treating the substrate comprises localized ionbombardment of a film deposited on the substrate.
 10. The method ofclaim 8, wherein the position of each beam of the second plurality ofbeams on the recording surface and the position of each beam of thethird plurality of beams on the recording surface each comprise aposition of a centroid of the corresponding beam on the recordingsurface.
 11. The method of claim 10, wherein comparing the individualposition of each beam of the second plurality of beams to the theindividual position of the corresponding beam of the third plurality ofbeams comprises determining a vector from the centroid of each beam ofthe third plurality of beams on the recording surface to the centroid ofeach corresponding beam of the second plurality of beams on therecording surface.
 12. The method of claim 8, wherein a film isdeposited on a second surface of the substrate and the first surfaceopposes the second surface, and treating the substrate comprisestreating substrate without moving the substrate from a substrate supporton which the substrate was supported when the first plurality of beamswere transmitted to the first surface of the substrate.
 13. The methodof claim 8, wherein treating the substrate comprises localized heatingof a film deposited on the substrate.
 14. The method of claim 11,further comprising calculating a local slope of the first surface foreach location on the first surface on which the first plurality of beamsare received based on the determined vectors.